Directly Driven Seed Meter Hub Drive

ABSTRACT

A direct drive electric seed metering system is provided for use with a row crop planter or seed planter that intakes a volume of multiple seeds from a seed hopper, draws individual seeds from the volume of multiple seeds and discharges them into a seed furrow formed in an agricultural field. The direct drive electric seed metering system includes a meter assembly having a meter housing and a seek disk rotatably mounted concentrically in the housing for singulating the seeds. A direct drive mechanism is mounted to the meter assembly for interfacing and driving the seek disk at an angular velocity which corresponds to the travel velocity of the seed planter. A single seed planter can have multiple direct drive electric seed metering systems, and each of the multiple direct drive electric seed metering systems preferably has its own prime mover to effectuate driving the seek disk.

BACKGROUND OF THE INVENTION

The invention relates generally to seed planters for dispensingindividual seeds at a controlled rate into a seed furrow, and inparticular, to a device and corresponding method for metering seeds at adesired rate.

Modern row crop planters or seed planters include multiple row plantingunits attached to a toolbar and towed behind a tractor. Each of the rowplanting units are responsible for opening a seed trench or furrow,dispensing the seeds into the furrow, then closing the furrow after theseeds are planted. The seed furrows are opened by a first pair of discsextending down from the planter at its leading end, closed by a secondpair of discs extending down from the planter at its trailing end, andthen tamped down by a trailing wheel which follows both disc pairs.

Typically, each row planting unit has its own seed hopper and seedmetering system for dispensing the seeds at a controlled rate into theseed trench or furrow as the planter advances along the ground. The mostcommon seed metering systems are vacuum-type meters that use vacuumforce to draw air through multiple openings in a rotating seed disc,trapping individual seeds within each opening for delivery to a secondlocation for their release to a seed placement device. The individualseeds are then delivered by the seed placement device, between thefurrow opening disc and the furrow closing discs, into the open furrowat a controlled rate.

To perform the various seed metering operations, conventional row cropplanters utilize a vacuum typically provided by a blower driven by ahydraulic motor attached to the hydraulic system of the tractor.However, the force required to rotate the seed disc is typicallyprovided by a ground drive or a hydraulic drive. The ground drive,hydraulic drive, or other power source rotates a main, common driveshaftextending substantially the entire width of the row crop planter. Theindividual seed metering systems of the individual row planting unitstake power from this main driveshaft. The power is transmitted from themain driveshaft to the individual row planting units by way of chain orcable drives, driving a meter driveshaft, whereby the meter driveshaftserves as a power accepting jackshaft.

Typical meter driveshafts extend axially from, and concentrically drive,the seek disk. Some attempts have been previously made to improve thecompactness of seed metering systems by moving the meter driveshaft froma concentric drive interface to a perimeter drive interface. Knownperimeter drive systems still rely on a main driveshaft serving as acommon power source for all the row planting units within a row cropplanter. Although such previous perimeter drive units may improvecompactness of seed metering systems to some extent, they fail toaddress numerous issues associated with operational uniformity of seedmetering systems.

In modern farming practices, there is an increased reliance uponprecision planting methods. Correspondingly, the integrity of modernseed metering system operations are closely related to systemefficiency, consistency, accuracy, repeatability, and thus uniformity inplacing seeds during use. Known seed metering systems, concentric driveand perimeter drive alike, face various performance uniformity issuesrelated to the operation of conventional main, common driveshaft andmeter driveshaft linkages. For example, the torque required to drive allof the seed metering systems by a common main driveshaft can besignificant, since each seed metering system can experience high levelsof friction during operation as, e.g. the vacuum force pulls the seekdisk toward and into contact with the meter housing. As another example,non-uniform operation can result from non-desired rotational drive speedvariations realized at the meter driveshaft as the chains and/or cablesflex, relax, tighten, and slacken as the row crop planter traversessomewhat irregular field surfaces. Any of these and other operatingcharacteristics can lead to erratic seed placement.

Additionally, typical seed planters do not have the ability todeactivate individual row planting units, independently of one another.This can lead to overseeding or overplanting, dispensing more seed thanneeded, during various instances in which portions of the seed planterpasses over a segment of the field more than once. Such instancesinclude those in which point rows are commonly utilized, such as whileworking fields having irregular shapes, or fields with trees or otherobstacles therein. Other such instances include various field turn areassuch as turn rows, headland rows, or end rows. Some efforts have beenmade to deactivate individual row planting units. However, such effortsrequire the use of complex assemblies, for example, pneumatic clutchassemblies with numerous parts and which can require relatively largeamounts of energy to operate.

There is a need for a seed metering system that provides improveduniformity of seed placement during row crop planting. There is also aneed for a seed metering system that reduces the number of moving partsand complex mechanical linkages in a seed planter. Furthermore, there isa need for seed planters which include multiple seed metering systemswhich can be activated and deactivated independently of each other sothat individual row planting units can be engaged or disengagedindependently as desired, whereby overplanting can be managed andminimized.

SUMMARY OF THE INVENTION

The present invention provides a direct drive electric seed meteringsystem which meets the desires and needs described above, while beingused, for example, in combination with a row crop planter or seedplanter. In a first embodiment of the present invention, a direct drivemechanism for use with a seed metering system is provided. The seedmetering system can be of the vacuum-type and can have a meteringhousing that encapsulates a seek disk. The seek disk is rotatable and isadapted to transfer individual seeds from one portion of the meteringhousing to another where they are discharged. In vacuum-typeimplementations of the seed metering systems, the seed transfer by theseek disk is aided by vacuum or negative pressure holding the seedsagainst the seek disk.

It is contemplated for the direct drive mechanism to be provided with adrive housing and prime mover attached to the drive housing. The drivehousing is preferably attached to the metering housing. In such aconfiguration, the prime mover can drive an output gear that, in turn,drives the hub for the seed disc or plate to which the seek disk ismounted. As desired, the prime mover can be an electric motor,preferably a 12V DC electric motor. In some implementations, the outputshaft of the prime mover can have a pinion gear mounted thereto, whichdirectly drives the seek disk hub.

In still further implementations, the direct drive mechanism interfaceswith the outer circumferential surface of the seek disk and selectivelyrotates it. Such an interfacing relationship can be realized between thehub of the seek disk and a pinion gear driven by the prime mover.Accordingly, the outer circumferential surface of the seek disk hub andthe outer circumferential surface of the output gear have correspondingstructures which facilitate the transfer of force therebetween. As oneexample, the outer circumferential surfaces can have spur gear teeth,interfacing and meshing with each other. As another example, the outercircumferential surfaces can have helical gear teeth interfacing andmeshing with each other.

In yet a further implementation, the seed disc is mounted to a seed dischub, which are collectively mounted to a shaft by a bearing assembly.The seed disc hub has an outer circumferential surface that is formed tointerface with an output gear that is directly driven by motor driveshaft. In one example, the circumferential surface and the output gearhave corresponding structures that interface with one another such thatthat rotation of the output gear causes rotation of the seed disc hub.

Other objects, features, and advantages of the invention will becomeapparent to those skilled in the art from the following detaileddescription and accompanying drawings. It should be understood, however,that the detailed description and specific examples, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not of limitation. Many changes and modifications maybe made within the scope of the present invention without departing fromthe spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments of the invention are illustrated in theaccompanying drawings in which like reference numerals represent likeparts throughout.

FIG. 1 illustrates a side elevational view of a portion of a seedplanter incorporating a first embodiment of direct drive electric seedmetering systems in accordance with the present invention.

FIG. 2 illustrates a side elevational view of the direct drive electricseed metering system shown in FIG. 1, with the metering cover removed.

FIG. 3 illustrates a side elevation of the direct drive electric seedmetering system, shown in FIG. 2, with the seek disk removed.

FIG. 4 illustrates a cross-sectional view of a portion of a direct driveelectric seed metering system taken at line 4-4 in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and specifically to FIG. 1, a portion of amultiple row crop planter implement or seed planter 5 is shown. The seedplanter 5 is typically pulled by a tractor or other traction device (notshown). Seed planter 5 includes a toolbar 8 that holds multipleindividual row planting units 10, each row planting unit 10 beingsubstantially identical. Only a single row planting unit 10 is shown forsimplicity.

Row planting unit 10 includes a frame 12 that attaches the unit 10 totoolbar 8 by way of parallel linkages 15. Row planting unit 10 has aleading end 17 which faces the direction of travel, indicated by arrow20. A trailing end 18 faces the opposite direction, away from thedirection of travel 20. Frame 12 supports a furrow opening mechanism 22near the leading end 17 of row planting unit 10, for cutting open thefurrow to receive the deposited seeds. As is known in the art, thefurrow opening mechanism 22 includes a pair of lateral spaced furrowopener discs 23, a furrow forming point, and an opener shoe 24.Optionally, the row planting unit 10 can include a runner-type openerfor providing a furrow in the ground.

A furrow closing mechanism 25 is located at the opposing end of theplanting unit 10, near trailing end 18. Closing mechanism 25 includes apair of furrow closer discs 26 and a trailing wheel 28. The closer discs26 are mounted in front of the trailing wheel 28, such that the twodefine a fore and aft aligned relationship relative each other.Correspondingly, after the closer discs 26 close the furrow, thetrailing wheel 28 rolls over and tamps the furrow down.

In some implementations, an optional pesticide hopper 29 sits atop theframe, at the trailing end 18. Pesticide hopper 29 contains, e.g., anherbicide or an insecticide, and is provided with conventionaldispensing means for applying controlled amounts of the contents in thedesired locations while using seed planter 5.

Seed hopper 30 is mounted atop frame 12, as is optional herbicide orpesticide hopper 29. Seed hopper 30 holds the seed supply for plantingby the row planting unit 10. The particular seed hopper 30 shown in FIG.1 is adapted and configured to store the seed material andgravitationally deposit the seed material to the seed metering system50, and ultimately to the ground as the seed planter 5 moves over andacross the field. This procedure is explained in greater detailelsewhere herein. In other implementations, the seed supply is held in aprimary seed hopper at a remote location, distant the various rowplanting units 10, whereby the seeds are supplied to the row plantingunits 10 pneumatically, or otherwise, through a seed conduit.

Regardless of the particular configuration of seed hopper 30, the seedsare directed from the seed hopper 30 to the seed metering system 50. Asbest seen in FIGS. 1-2, seed metering system 50 includes vacuum port 52,singulator assembly 55, seed inlet 57, meter housing 60, seek disk 70seek disk hub 71, and direct drive mechanism 100. The seek disk 70 ismounted to the outer face of the seek disk hub 71 and rotates with theseek disk hub 71. Vacuum port 52 extends from the cover 64 and isconnected to a vacuum source (not shown). Singulator assembly 55 isattached to the meter housing 60 and is adapted and configured toinhibit more than one seed from being discharged from the seed meteringsystem 50 per seed discharge event. Seed inlet 57 is an elongatedopening or conduit extending and directing seeds between the seed hopper30 and meter housing 60. In such configuration, the seeds move by way ofgravity from the seed hopper 30 through seed inlet 57 and into areservoir or void space within the meter housing, such as meter cavity61.

Meter housing 60 has a back portion 62 and a front or cover portion 64,which are preferably integrally formed with one another to define ameter cavity 61 therebetween. The meter cavity 61 houses the seek disk70 therein. The seek disk hub 71 is mounted to an axle 73 by a pin (FIG.4) and the axle is mounted in a conventional manner by a bearingassembly 77, and the axle extends into the housing 60. As seen in FIG.1, vacuum port 52 extends outwardly from cover portion 64 of the housing60 and as seen in FIG. 2, seed inlet 57 extends from backing portion 62of the housing 60. In this configuration, it is apparent that the vacuumport 52 and seed inlet 57 are positioned on opposing sides of the seekdisk 70. As desired, the vacuum port 52 and seed inlet 57 are at leastpartially registered with each other, on opposing sides of the seek disk70. An opening 65 passes through the meter housing 60 permitting, e.g.,portions or components of the direct drive mechanism 100 to extend intothe meter cavity 61 and cooperate and interface with the seek disk hub71.

The seek disk 70 is a flat, disc-like member, having opposing front andback surfaces 72 and 74, respectively. Seed pockets 76 are discreteopenings that extend between front and back surfaces 72, 74, and thusthrough the entire thickness of the seek disk 70. The seed pockets 76are equally spaced from each other and are radially spaced equidistantfrom an axis of rotation of the seek disk 70.

Seeds are guided, by the seed inlet 57, from seed hopper 30 to the metercavity 61, generally into the space between the back surface 74 of seekdisk 70 and the inwardly facing surface of back portion 62 of thehousing 60. The seek disk 70 rotates in the meter cavity 61 as it isdriven by the seek disk hub 71, whereby the seed pockets 76 pass acrossand interface the seeds which accumulate in the meter cavity 61. Invacuum-type implementations of the seed metering system 50, the vacuumor negative pressure is drawn through the vacuum port 52 and thus alsothrough the seed pockets 76. In other words, vacuum or negative pressureis drawn from the beyond the front surface 72 which draws the seeds intothe seed pockets 76, against the back surface 74 of seek disk 70.Regarding the particular vacuum-based methods and devices to applynegative pressure or vacuum to the seek pockets 76, any of the variousconventional vacuum-based seed metering techniques will suffice.

The vacuum holds the seeds in the seed pockets 76 where they arerotatably transported in unison with the rotation of seek disk 70. Asthe seeds rotate with seek disk 70, and thus as they approach thedischarge portion of the seed metering system 50, the seeds encounterthe singulator assembly 55. Singulator assembly 55 is a conventionalseed singulator device which insures that one and only one seed ispresent in each seed pocket 76 as each particular seed pocket 76approaches the discharge area of the seed metering system 50, fordispensation through seed tube 80. The seeds that are delivered intoseed tube 80 are deposited into the furrow, between the furrow openingand closing mechanisms 22 and 25, respectively. Seed tube 80 is agenerally upright or vertical passage, which directs the seed to theground or furrow for planting.

Turning now to FIGS. 3-4, seek disk 70 is rotated by way of its drivencooperation with the seek disk hub 71, which is in turn driven by thedirect drive mechanism 100. Direct drive mechanism 100 selectivelyrotates or drives the seek disk hub 71 at a variable speed. Theparticular speed at which speed plate hub 71 is driven by the directdrive mechanism 100 is related, at least in part, to the ground speed ortravel velocity of seed planter 5. The direct drive mechanism 100includes prime mover 110 and a drive output assembly 120. Prime mover110 is preferably an electric motor with an output shaft 112, and, morepreferably, a 12V DC electric motor with an output shaft 112. The primemover 110 is operably connected to a controller 115 and a power supply117 (FIG. 1) which can be electrically connected to the 12V DCelectrical system of the tractor. The controller 115 is further operablyconnected, in a conventional manner, to any of a variety of suitablesensors for sensing, e.g., travel velocity of the row crop planter 10,and/or other operating characteristics, which will be evaluated by thecontroller 115 in determining the desired rate of rotation of seek disk70 by energizing direct drive mechanism 100.

In an alternate embodiment, the prime mover is a 3 phase motor. In yetanother embodiment, the prime mover is a stepper motor. It is alsocontemplated that the prime mover could drive the seek disk hub 71 witha worm gear.

The particular configuration of drive output assembly 120 is selectedbased on the operating characteristics of prime mover 110 and seek diskhub 71. In preferred embodiments, drive output assembly 120 provides anoutput gear 125. The output gear 125 is mounted concentrically to theprime mover 110 output shaft 112 and it directly interfaces with anddrives the geared outer circumferential surface 75 of seek disk hub 71.In a preferred implementation, the output gear 125 is a pinion gear.

In one preferred implementation, the prime mover 110 optimally functionsat operational speeds of about 500-600 rpm. In this regard, the diameter(e.g., gear ratio) of the output gear 125 and the seek disk hub 71 areselected to mechanically step down the 500-600 rpm shaft speed of primemover 110 to the desired 60 rpm maximum rotational speed of the seekdisk hub 71, ensuring the desired rotational operation speeds of seekdisk 70.

It will therefore be appreciated that the output gear 125 and the gearedouter circumferential surface 75 of seek disk 71 are configured in acooperating, force transmitting, preferably gear teeth meshing manner.Accordingly, outer circumferential surface 75 and the outercircumferential surface of output gear 125 can have cooperating, e.g.,spur gear teeth, helical gear teeth, or suitable force transmittingconfigurations.

It is apparent that direct drive mechanism 100 eliminates, mitigates, orotherwise reduces the need for a typical main driveshaft, common to allrow planting units 10 of the seed planter 5. Direct drive mechanism 100further eliminates, mitigates, or otherwise reduces the need for any,e.g., meter driveshaft or jackshaft to drive the seek disk 70. This isbecause each row planting unit 10 has its own direct drive mechanism 100attached directly thereto, and each direct drive mechanism 100 has itsown prime mover 110. In this configuration, there is no need for acommon source of mechanical energy to power the drive assemblies 100through, e.g., chains, cables, or other mechanical linkages. Rather, thenumber of drive assemblies 100 and the number of prime movers 110corresponds to, preferably are equivalent to, the number of row plantingunits 10 utilized by the seed planter 5.

In light of the above, during use, the desired seed type is receivedfrom the seed hopper 30, through the inlet 57, into the seed meteringsystem 50. Simultaneously, furrow opening mechanism 22 opens a trough orfurrow to receive seeds. Drive mechanism 100 rotates the seek disk 70 byenergizing the prime mover 110, rotating its output shaft 112. Theoutput shaft 112 rotates the output gear 125, which correspondinglyrotates the seek disk hub 71. The teeth of output gear 125 mesh with anddrive the corresponding teeth on the geared outer circumferentialsurface 75 of the seek disk hub 71.

Vacuum is applied from the front surface 72 of the seek disk 70, drawnthrough the seed pockets 76, thereby drawing seeds from the meter cavity61 into the seed pockets 76. As desired, in some configurations, apositive pressure airflow can be provided toward the back surface 74 toenhance the transfer of seeds from the meter cavity 61 to the seedpockets 76. The seek disk continues to rotate which draws the seeds inthe seed pockets 76 radially away from the mass of accumulated sees inthe meter cavity 61. All but one seed per seed pocket 76 are removed bythe singulator assembly 55, and each such single seed is ultimatelydischarged from the system 50 through seed tube 80 into the furrow. Asthe seed planter 5 advances further, the furrow closing mechanism 25closes the furrow with the seeds therein and the trailing wheel 28 tampsdown the closed furrow.

All the while, the controller 115 (FIG. 1) monitors the ground speed ortravel speed of the seed planter 5, the rotational velocity of the seekdisk 70 or the seed depositing rate from seed metering system 50, and,as required, adjusts or regulates the operating characteristics of theseed metering system 50 to suitably correspond to the ground speed. Itwill be appreciated that the ground speed of the seed planter 5 can bedetermined in a sensor mounted to a gauge wheel (now shown) of theplanter 5. The ground speed could also be measured using GPS technologyor other known techniques. The desired instantaneous seed depositingrate measured by seed sensor (not shown) on seed tube 80 is a functionof the travel velocity of the seed planter 5 at that instant, wherebysuch desired depositing rate can be predicted and sought by thecontroller. Accordingly, the seed metering system 50 is selectivelydriven by drive assembly 100, preferably at a variable rate and, morepreferably, at an infinitely variable rate, based at least in part onthe ground speed or travel velocity of seed planter 5. It is furthercontemplated that a sensor (not shown) may be disposed in each housing60 that provides feedback to the controller 115 regarding the rotationalspeed of the output gear 125, the seek disk hub 71, or both.

Furthermore, preferred implementations include a single controller 115which controls all of the drive assemblies 100, and thus, the operatingcharacteristics of all of the seed metering systems 50. Doing so canensure that each drive assembly 100 receives the same control signals,whereby the resultant output responses of the assemblies 100 should besubstantially analogous, when that is desired. This can enhanceuniformity of seed placement between the individual rows and otheroperating characteristics.

However, controller 115 can also control the individual drive assemblies100 independently of each other, optionally each row planting unit hasits own controller 115. In such configuration, the row planting units 10can be activated and deactivated independently of each other, wherebyoverplanting can be managed and minimized. Accordingly, when using rowcrop planting techniques such as, e.g., planting point rows, turn rows,headland rows, or end rows, or in other situations which could lead todouble planting or other overplanting conditions, the precision plantingsystem can automatically de-energize and thus disengage any one or moreof the individual row planting units as desired. This enables the userto comprehensively manage the application of seed, on a per row plantingunit and thus per row basis. Moreover, since each row has its owncontroller, the user can apply seed at different population rates oneach individual row, as desired. This can be particularly beneficial togrowers that grow seed corn for the industry and are planting differentvarieties, or “male only” seeds, or otherwise desire differentpopulation rates in the individual row planting units 10 on the planter5.

It will be appreciated that the present invention provides a number ofadvantages over seed metering systems that drive the seed disk directly.For example, the seed disk hub of the present invention has a thickerprofile than the seed disk. This thicker profile provides gear teethhaving a wider surface area and thus reduces the wear on the gear teeth.Additionally, for those disks that are directly driven, it is necessaryto cut gear teeth into the seed disks. Thus, to retrofit an existingseeder, it is necessary to replace the existing seed disk with a diskhaving gear teeth. Since each crop type typically requires its own seeddisk, the replacement costs can be quite high. The present invention isusable with conventional seed disks and thus retrofitting can beaccomplished at far less a cost. Also, when the seed disk, as opposed tothe seed disk hub, engages the drive gear, it is necessary to disengagethe gear drive from its engagement with the seed disk to replace orservice the seed disk. In contrast, the present invention allows theseed disk to be detached from the seed disk hub and a new seed diskmounted to the hub without disengaging the hub from the gear drive.

While the invention has been shown and described with respect toparticular embodiments, it is understood that alternatives andmodifications are possible and are contemplated as being within thescope of the present invention. A wide variety of ground-engagingimplements (e.g., conventional seeders, seed planters, and row cropplanters) can employ the direct drive electric seed metering system 50of the present invention. In addition, it should be understood that thenumber of direct drive electric seed metering systems 50 employed on therow crop planter or seed planter 5 is not limiting on the invention.

Many changes and modifications could be made to the invention withoutdeparting from the spirit thereof. The scope of these changes willbecome apparent from the appended claims.

1. A direct drive mechanism for use with a seed metering system having ametering housing, a seek disk, and seed hub to which the seek disk ismounted therein, comprising: a drive housing attached to the meteringhousing; a prime mover attached to the drive housing; and an output gearinterconnected to the prime mover and the seed hub, and operative to bedirectly driven by the prime mover and configured to directly drive theseed hub when caused to rotate by the prime mover.
 2. The direct drivemechanism of claim 1, wherein the prime mover is an electric motor. 3.The direct drive mechanism of claim 1, wherein the prime mover is a 12VDC electric motor.
 4. The direct drive mechanism of claim 3, wherein theelectric motor is a variable speed motor.
 5. The direct drive mechanismas in claim 1, wherein the output gear is a pinion gear having teeththat interface with teeth of the seed hub, and extends into the meteringhousing.
 6. The direct drive mechanism of claim 1, wherein the primemover has a rotatable output shaft and the output gear is mountedthereto.
 7. The direct drive mechanism of claim 1, wherein the outputgear drives the seed hub by way of a gear meshing interface.
 8. A seedplanter, comprising: a toolbar generally defining a width dimension ofthe planter and configured to be coupled to a towing vehicle; aplurality of row planting units mounted to the toolbar, laterally spacedfrom each other, and each having a seed metering system, wherein eachseed metering system includes a seed disc that meters a volume of seedand a seed disc hub to which the seed disc is mounted; and a pluralityof direct drive mechanisms, each direct drive mechanism directly drivinga corresponding seed metering systems, and wherein each direct drivemechanism includes a prime mover having an output shaft that drives anoutput gear in direct engagement with the seed disc hub to causerotation of the seed disc.
 9. The seed planter of claim 8, wherein eachprime mover is an electric motor.
 10. The seed planter of claim 9,wherein each electric motor is a variable speed electric motor.
 11. Theseed planter of claim 8, wherein each metering system has a meteringhousing and each direct drive mechanism has a drive housing, respectivemetering and drive housings being connected to each other.
 12. The seedplanter of claim 11, wherein each of the output gears is a pinion gear.13. The seed planter of claim 11, wherein the seed metering systems arevacuum systems.
 14. The seed planter of claim 11, further comprising asensor disposed in each of the metering housings, and each sensor isoperative to provide feedback regarding a rotational speed of arespective output gear.
 15. The seed planter of claim 8, wherein theprime mover has an output shaft that is rotated at a variable speed, andthe output gear provides a speed reduction such that the seed disc hubis caused to selectively rotate at a rotational speed between 0 and 60r.p.m.
 16. A seed disc assembly for metering seed from an agriculturalimplement, comprising: a seed disc configured to rotate within a housingand during said rotation meter seed from a volume of seeds containedwithin the housing; and a seed disc hub to which the seed disc ismounted, the seed disc hub having an outer circumferential surfaceconfigured to interface with a gear driven by an electric motor.
 17. Theseed disc assembly of claim 16, wherein the outer circumferentialsurface includes an outer peripheral edge, and having a plurality ofteeth formed about the outer peripheral edge.
 18. The seed disc assemblyof claim 17, wherein the seed disc and the seed disc hub each have anopening centered about an axis of rotation, and wherein the openingsfacilitate mounting of the disc hub and the seed disc onto a supportshaft.
 19. The seed disc assembly of claim 18 further comprising abearing configured to rotatably couple the seed disc hub to the supportshaft.
 20. The seed disc assembly of claim 18 further comprising a seeddisc housing containing the seed disc, the seed disc hub, and the gear,and wherein the seed disc housing is arranged such that electric motoris external to the seed disc housing.